UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC  20460

OFFICE OF PREVENTION,

PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

Date:	9 September 2009

Subject:	Tribenuron Methyl.  Petition   SEQ CHAPTER \h \r 1 to Establish
New (and Amend Several Existing) Permanent Tolerances for Residues
Associated with Food/Feed Use of the Herbicide on Genetically Modified
Soybeans and Field Corn.  Summary of Analytical Chemistry and Residue
Data. 

™ Express®



FROM:	  SEQ CHAPTER \h \r 1 William T. Drew, Chemist

		Alternative Risk Integration and Assessment (ARIA) Team 

		Risk Integration, Minor Use and Emergency Response Branch (RIMUERB) 

		Registration Division (RD), 7505P

THRU:	Michael A. Doherty (PhD), Senior Scientist

		Risk Assessment Branch 2 (RAB2)

		Health Effects Division (HED), 7509P

TO:		Breann Hanson, Biologist

		ARIA/RIMUERB/RD, 7505P

		and

		James Tompkins and Vickie Walters, RM Team 25  SEQ CHAPTER \h \r 1  
SEQ CHAPTER \h \r 1 

		Herbicide Branch (HB)/RD, 7505P

Executive Summary

	Tribenuron methyl is a   HYPERLINK
"http://www.alanwood.net/pesticides/class_herbicides.html" \l
"triazinylsulfonylurea_herbicides" \t "_top"  triazinylsulfonylurea
herbicide  that inhibits acetolactate synthase (ALS).  Tribenuron methyl
is currently registered to DuPont Crop Protection, as dry flowable (DF),
or water-soluble granule (SG) formulations, for use on a variety of
grain and seed crops, as well as on cotton and flax.  

	DuPont has submitted 6 volumes of crop field trial, processing, and
metabolism (laying hen) data in support of two petitions, PP#8F7432 and
PP#8F7441, to establish tolerances for residues of tribenuron methyl in
soybean and field corn commodities.  Section F of PP#8E7432 has proposed
the establishment of tolerances for residues of the herbicide tribenuron
methyl (with CAS Name
methyl-2-[[[[[4-methoxy-6-methyl-1,3,5-triazin-2-yl] methylamino]
carbonyl] amino] sulfonyl] benzoate, and CAS Number 101200-48-0) in or
on soybean commodities, at the levels listed below.  

Soybean, hay	0.25 ppm

Soybean, forage	0.06 ppm

Soybean, seed	0.01 ppm

Soybean, hulls	0.04 ppm

Soybean, aspirated grain fractions	3.46 ppm

	Section F of PP#8E7441 has proposed the establishment of tolerances for
residues of the herbicide tribenuron methyl in or on field corn
commodities, at the levels listed below.  

Corn, field, grain	0.01 ppm

Corn, field, forage	0.2 ppm

Corn, field, stover	1.1 ppm

Corn, field, aspirated grain fractions	3.55 ppm

™ Express®, an SG formulation containing 50% of the active ingredient
(ai), tribenuron methyl.  Express® is proposed for use as one or two
foliar spray treatments to genetically modified soybeans or field corn,
at a maximum single (and seasonal) use rate of 0.03125 pounds of ai per
acre (lb ai/A), which corresponds to the proposed label’s stated
maximum use rate of 1 ounce of EP per acre per crop season.  The label
specifies pre-harvest intervals (PHIs) of 7 days for field corn
commodities, and 14 days for soybean forage and hay.  As the label
directions for use on soybeans prohibit applications after the R2 stage,
a specific PHI for soybean seeds was not proposed, and is not required. 
Re-treatment intervals (RTIs) for use on soybeans and field corn were
not specified.  

	Tribenuron methyl tolerances in plant commodities are listed in 40CFR
§180.451[a] and [c]; they are currently expressed in terms of the
parent compound, tribenuron methyl.  

	  SEQ CHAPTER \h \r 1 The nature of the residue in plants is adequately
understood.  HED has determined that, in target crops, tribenuron methyl
per se is the residue of concern (ROC) for purposes of risk assessment
and tolerance expression.  

	There are significant livestock feedstuffs associated with the proposed
use patterns on soybeans and field corn.  Based on the data from the
goat metabolism study, ARIA/RD and HED conclude that a cattle feeding
study is not required for this petition.  Based on the data from the
poultry metabolism study, residues in liver resulting from the 10X
dosing level would be 0.012 ppm.  Normally, a poultry feeding study
would be required (due to residues being detected above 0.01 ppm at the
10X dosing level), but none were previously requested.  Because no
significant poultry feed items are associated with the current
petitions, a poultry feeding study is not required at this time. 
However, should the registrant submit any future petition proposing use
on a commodity (or commodities) associated with poultry feed items, a
poultry feeding study will be required, and that study should be
submitted in conjunction with any such petition.  

	Adequate confined rotational crop data are available to support a
minimum 30-day plantback interval (PBI) for all crops without registered
uses.  As labels for tribenuron methyl currently specify minimum PBIs of
no less than 60 days for canola, rape, and sugar beets, and 45 days for
all other crops not listed on the label, data requirements for
rotational crops are fulfilled, and tolerances are not required in
rotational crops.  

	Several adequate analytical   SEQ CHAPTER \h \r 1 methods are available
for enforcing tolerances for tribenuron methyl in plant commodities. 
Residues in samples from the soybean and field corn field trials
associated with these petitions were determined using a liquid
chromatography with tandem mass-spectrometric detection (LC/MS/MS)
method, DuPont Method 13412 (Revision 1).  This method was adequately
validated prior to, and in conjunction with, the field trial analyses;
the validated limit of quantitation (LOQ) is 0.010 ppm for tribenuron
methyl in all corn and soybean commodities.  

	The available data indicate that residues of tribenuron methyl are not
recovered by the FDA multiresidue methods.  

	The available storage stability data adequately support the sample
storage durations and conditions incurred during the corn and soybean
field trial and processing studies.  

	The available corn and soybean field trial data are acceptable, and
support the proposed use patterns for tribenuron methyl (50% ai SG) on
genetically modified soybeans and field corn.  An adequate number of
trials were conducted on each crop in the appropriate geographical
regions.  All samples were analyzed for the ROC using an adequate
method, and sample storage conditions and durations are supported by the
available storage stability data.  The data support tolerances of 0.01
ppm in/on corn grain, 0.15 ppm in/on corn forage, 1.1 ppm in/on corn
stover, 0.01 ppm in/on soybean seeds, 0.07 ppm in/on soybean forage, and
0.35 ppm in/on soybean hay.  

	The available corn and soybean processing data for tribenuron methyl
are adequate.  As residues were <LOQ in corn grain, and all corn
processed fractions following an application at 5X the proposed use
rate, separate tolerances are not required in corn grain processed
fractions.  For soybeans, residues concentrated only in hulls (4.05X). 
Based on HAFT residues of 0.01 ppm for soybean seeds (14-day PHI), the
tolerance in/on soybean hulls should be set at 0.04 ppm.  

	Tribenuron methyl residues were shown to concentrate in aspirated grain
fractions (AGF) from both field corn grain (13X), and soybean seeds
(150X).  Based on the HAFT residues of field corn grain (0.01 ppm), and
soybean seeds (0.01 ppm), the maximum expected residues would be 0.13
ppm in AGF from corn grain, and 1.5 ppm in AGF from soybean seeds.  As
residues in soybean AGF are higher than in corn grain AGF, the tolerance
in/on AGF should be set at 1.5 ppm.  

	There are no established nor proposed Codex or Mexican maximum residue
limits (MRLs) for residues of tribenuron methyl (Appendix II).  Canada
has established MRLs for tribenuron methyl in several plant commodities.
 However, no Canadian MRLs for tribenuron methyl have been proposed nor
established in the commodities being considered under these petitions. 
Therefore, there are no concerns regarding compatibility of the proposed
tolerances.  

	An analytical standard for tribenuron methyl is currently available in
the National Pesticide Standards Repository.  

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

	Pending submission of revised Sections F, there are no residue
chemistry issues that would preclude the establishment of permanent
tolerances for tribenuron methyl residues in soybean and field corn
commodities.  Provided that the forthcoming human health risk assessment
does not identify any issues of concern, the submitted data support
tolerances for residues of tribenuron methyl, including its metabolites
and degradates, in or on soybean and field corn commodities, at the
levels listed below. Compliance with the tolerance levels specified
below is to be determined by measuring tribenuron methyl only.  

Soybean, hay	0.35 ppm

Soybean, forage	0.07 ppm

Soybean, seed	0.01 ppm

Soybean, hulls	0.04 ppm

Corn, field, grain	0.01 ppm

Corn, field, forage	0.15 ppm

Corn, field, stover	1.1 ppm

Grain, aspirated fractions	1.5 ppm

	860.1480 Meat, Milk, Poultry, and Eggs

	Based on the data from the poultry metabolism study, residues in liver
resulting from the 10X dosing level would be 0.012 ppm.  Normally, a
poultry feeding study would be required (due to residues being detected
above 0.01 ppm at the 10X dosing level), but none were previously
requested.  Because no significant poultry feed items are associated
with the current petitions, a poultry feeding study is not required at
this time.  However, should the registrant submit any future petition
proposing use on a commodity (or commodities) associated with poultry
feed items, a poultry feeding study will be required, and that study
should be submitted in conjunction with any such petition.  

	860.1550 Proposed Tolerances

	The petitioner should submit revised Sections F to correct the
tolerance levels in field corn forage (PP#8F7441), and soybean forage
and hay (PP#8F7432), and to correct the commodity definition for AGF
(PP#8F7432 and PP#8F7441), as recommended in Table 9, on page 19.  

Other Considerations

	DuPont Method 13412 (Revision 1) has been amended to include comments
from the ILV, so it can now be forwarded to FDA for use as an
enforcement method.  

Background

	Tribenuron methyl is a sulfonylurea herbicide (Group 2) that works via
inhibition of ALS.  It is currently registered for post-emergence
application(s) to barley, canola, cotton, flax, oats, sunflower, wheat,
and grasses grown for seed, for the selective control of broadleaf
weeds.  It is also registered for use as a pre-emergence burndown
broadcast application for wheat and barley, and as a preplant or
at-planting burndown application for cotton, field corn, rice, grain
sorghum, and soybeans.  Permanent tolerances are established for
residues of tribenuron methyl at levels ranging from 0.02 ppm in/on
cotton and canola commodities to 0.5 ppm in/on wheat hay (40CFR
§180.451[a] and [c]).  Tolerances have also been established at 0.05
ppm in/on field corn forage, grain and stover.  

	DuPont Crop Protection has submitted petitions supporting the use of
tribenuron methyl on soybeans and field corn that are genetically
tolerant to sulfonylurea herbicides (PP#8F7432 and PP#8F7441,
respectively).  These petitions have been submitted in conjunction with
related petitions for use of rimsulfuron and chlorimuron ethyl on
genetically modified soybeans and field corn in support of a future EP
containing all three sulfonylurea herbicides.  The chemical structure
and nomenclature of tribenuron methyl are presented in Table 1 (below). 
The physicochemical properties of the technical grade of tribenuron
methyl are presented in Table 2 (below).  

TABLE 1	Tribenuron Methyl Nomenclature.  

Chemical structure	



Common name	Tribenuron methyl

Molecular formula	C15H17N5O6S

Molecular weight	395.4

Company experimental name	DPX-L5300

IUPAC name
Methyl-2-[4-methoxy-6-methyl-1,3,5-triazin-2-yl(methyl)carbamoyl-sulfamo
yl]benzoate

CAS name
Methyl-2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)methylamino]carbonyl
]amino] sulfonyl]benzoate

CAS registry number	101200-48-0

End-use product (EP)	50% ai SG (DuPont Express herbicide; EPA
Registration #352-632)



TABLE 2	Physicochemical Properties of Tribenuron Methyl.  

Parameter	Value	Reference

Melting point/range	142ºC	MRID #47138301

pH (at 20ºC)	4.64

	Density  (at 19.6ºC)	1.4594 ± 0.001 g/cm3

	Water solubility (at 20ºC)	pH 5		0.0489 g/L

pH 7		2.04

pH 9		18.3

	Solvent solubility (at 20ºC)	Acetone			39.1 g/L

Acetonitrile		46.4

Dichloromethane		>250

Dimethylformamide	98.2

Ethyl acetate		16.3

n-Heptane		0.02

Methanol		2.59

n-Octanol		0.383

Xylene			13.1

	Vapor pressure (at 25ºC)	2.7 x 10-7 mm Hg

	Dissociation constant (pKa)	5.0

	Octanol/water partition coefficient, Log [KOW] (at 20ºC)	pH 5			2.60

pH 7			0.78

, λ)	pH 1.66		200, 231 nm

pH 7		201, 256 nm

pH 11.72	208, 256 nm

	

860.1200  Directions for Use

	There are currently 10 active EPs containing tribenuron methyl that are
registered to DuPont for post-emergence uses on wheat, barley and oats
(see Table 3, below).  These EPs are formulated as either DFs or SGs. 
Two of the EPs contain only tribenuron methyl at 50% or 75% ai, and five
of the EPs contain combinations of tribenuron methyl (10-37.5% ai), and 
thifensulfuron methyl (25-50% ai).  Two formulations contain
combinations of tribenuron methyl (13.6-18.75% ai), thifensulfuron
methyl (27.3-37.5% ai), and metsulfuron methyl (10.9-15% ai), and the
final formulation is comprised primarily of dicamba (63.6% ai), with no
more than 4.7% each of thifensulfuron methyl, tribenuron methyl, and
metsulfuron methyl.  

Affinity™	SG	10%	40%	--	--

352-661	Affinity™ GBF92	SG	25%	25%	--	--

352-714	Harmony( Extra	SG	16.67%	33.33%	--	--

352-715	Ally( Extra	SG	13.6%	27.3%	10.9	--

352-751	Agility™ SG	SG	2.4%	4.7%	1.9%	63.6%



	With the current petitions (PP#8F7432 and PP#8F7441), DuPont provided
an amended label for Express®, the SG formulation (EPA Registration
#352-632) containing 50% ai, intended for use on Optimum® GAT®
herbicide-tolerant soybeans and field corn.  The amended use directions
for modified soybeans and field corn are summarized in Table 4 (below). 


Table 4	Summary of Directions for Use of Tribenuron Methyl.  

Application Timing; Type; Equipment	Formulation

[EPA Reg. #]	Use Rate

(lb ai/A)	Number of Uses per Season	Maximum Seasonal Use Rate

(lb ai/A)	PHI 1

(Days)	Use Directions and Limitations 2

Soybean

Post-emergence (of crop and weeds); broadcast foliar; ground, air, or
chemigation equipment.  	50% ai SG

[352-632]	0.008-0.03	2	0.03	14	Add a non-ionic surfactant (NIS) at 0.25%
v/v, or a crop oil concentrate (COC) at 1.0% v/v.  

Field Corn

Post-emergence (of crop and weeds); broadcast foliar; ground, air, or
chemigation equipment.  	50% ai SG

[352-632]	0.008-0.03	2	0.03	7	Add an NIS at 0.25% v/v, or a COC at 1.0%
v/v.  

1. PHI = Pre-Harvest Interval.  

2. For applications up to 0.008 lb ai/A, sugar beet, winter rape, and
canola may be planted 60 days after application; 	other crops may be
planted 45 days after application.  For applications above 0.008 lb
ai/A, non-labeled 	crops may be planted 4 months after application.  

	Conclusions:  The label directions are adequate to allow evaluation of
the residue data relative to the labeled uses.  The available soybean
and field corn data support the proposed 7-day PHI for field corn, and
the proposed 14-day PHI for soybean.  

860.1300 Nature of the Residue - Plants 

	D304059; R. Griffin; 24 June 2004 

	PP#0F6135; D266130; C. Swartz; 25 July 2006

	The nature of the residue in plants is adequately understood, based on
metabolism studies with wheat, canola, cotton and soybeans.  The ROC in
plant commodities is tribenuron methyl per se.  

860.1300 Nature of the Residue - Livestock

	D304059; R. Griffin; 24 June 2004 

	DER for MRID #47637801 (NR in Laying Hens)

	The nature of the residue in ruminants is adequately understood, based
on an acceptable goat metabolism study.  The nature of the residue in
poultry is adequately understood, based on an acceptable laying-hen
metabolism study.  The ROC in ruminants and poultry is tribenuron methyl
per se.  

860.1340 Residue Analytical Methods

	D311607; S. Ary; 4 January 2005

	D304059; R. Griffin; 24 June 2004

	D266130; C. Swartz; 25 July 2006

	D330633; S. Hummel; 8 August 2006

	Enforcement methods:  A high-performance liquid chromatography with
photo-conductivity detection (HPLC/PC) method, Method AMR 337-85
(Revision A), is available for   SEQ CHAPTER \h \r 1 enforcement of
tolerances for residues of tribenuron methyl in grain, forage and straw
commodities.  For this method, residues are extracted with acetonitrile
(ACN), cleaned up using silica-gel chromatography, and analyzed by
HPLC/PC.  The method was validated by BEAD’s Analytical Chemistry
Branch (ACB) in wheat grain at 0.057 and 0.113 ppm, and in wheat straw
at 0.113 and 0.226 ppm.  The petitioner validated the method at
0.010-0.020 ppm in wheat and barley grains, at 0.020-0.040 ppm in wheat
and barley straws, and at 0.010-0.10 ppm in wheat forage.  

	A liquid chromatography with mass-spectrometric detection (LC/MS)
method, DuPont Method 1381, is also available for enforcement of
tolerances for residues of tribenuron methyl in canola, cotton and flax
commodities.  For this method, samples are extracted with an
ACN/ammonium carbonate buffer solution, and the concentrated residues
are reconstituted in methanol for analysis.  If required, a hexane wash
step, or cleanup step using a strong anion exchange SPE column, may be
incorporated.  Analysis is performed by column-switching liquid
chromatography.  Extracts in methanol are applied to a size exclusion
chromatography column, and the eluate is diverted onto a reversed phase
C8 column for MS analysis.  The validated LOQ was 0.020 ppm.  This
method may also be used for enforcing tolerances in corn grain, sorghum
grain, and soybean seeds.  

	Field trial samples were analyzed for all of the sulfonylurea residues
(chlorimuron ethyl, rimsulfuron, and tribenuron methyl) in soybeans and
field corn using a liquid chromatography with tandem mass-spectrometric
detection (LC/MS/MS) method, DuPont Method 13412 (Revision 1),
Analytical Method for the Determination of Nicosulfuron, Thifensulfuron
Methyl, Ethametsulfuron Methyl, Rimsulfuron, Tribenuron Methyl, and
Chlorimuron Ethyl in Oil Crop Matrices Using SPE Purification and
LC/MS/MS Detection.  For this method, samples are hydrated (corn grain
and stover, and soybean hay and seeds only) with potassium phosphate
buffer, and then extracted twice with acetonitrile (ACN)/K2HPO4 (3:1
v:v, pH 7) followed by centrifugation.  Residues were then cleaned up by
solvent partitioning and elution through a solid-phase extraction (SPE)
cartridge.  Residues were determined using external standards for
quantitation.  The LOQ in all corn and soybean commodities is 0.010 ppm,
while the limit of detection (LOD) is 0.003 ppm.  This method was
previously reviewed in conjunction with a petition for thifensulfuron
methyl (D330813; S. Hummel; 8 August 2006).  One of the comments from
that review stated that a new copy of the method was needed,
incorporating the comments from the independent laboratory validation
(ILV) laboratory.  The submitted copy of the method has been amended to
include comments from the ILV, so it can now be forwarded to FDA for use
as an enforcement method.  A PMV trial is not required.  

	An enforcement method for animal commodities is not currently required,
as there are no tolerances for tribenuron methyl residues in livestock
commodities.  

	Conclusions:  The available residue analytical method data are adequate
to satisfy data requirements for crops.  The existing tolerance
enforcement methods, Method AMR 337-85 (Revision A) and DuPont Method
1381, are adequate to enforce the proposed tolerances for grain, forage
and hay.  DuPont Method 13412 (Revision 1) is also adequate for
tolerance enforcement purposes.  

860.1360 Multiresidue Methods

	D304059; R. Griffin; 24 June 2004

	The FDA PESTDATA database, dated June 2005 (PAM Volume I, Appendix I),
does not contain any information regarding the recovery of tribenuron
methyl using multiresidue methods.  Data investigating the behavior of
tribenuron methyl using the FDA Multiresidue Methods have been submitted
by the registrant (MRID #40927202).  These data were apparently not
received by FDA for evaluation, despite being sent to Leon Sawyer, a
chemist with the Pesticides and Industrial Chemicals Branch of FDA’s
Division of Contaminants Chemistry, in a memo dated 22 March 1989.  The
results of the Multiresidue Methods study with tribenuron methyl will be
re-sent to the FDA.  The available data indicate that residues of
tribenuron methyl are not recovered by the FDA multiresidue methods.  

860.1380 Storage Stability

	D304059; R. Griffin; 24 June 2004

	D330633; S. Hummel; 8 August 2006

	DER for MRID #47542802 (CFTs with Soybeans)

	Adequate data are available indicating that tribenuron methyl is stable
under frozen storage conditions for at least 4 months in corn stover and
soybean seeds, 6 months in corn forage, 8.6 months in sunflower seeds,
14 months in cottonseeds and cotton gin byproducts, and 21 months in
wheat grain and straw.  

	To support the storage duration for soybean seeds, a concurrent freezer
storage stability study was conducted using control samples of
homogenized soybean seeds fortified with tribenuron methyl at 0.10 ppm. 
The fortified samples were stored under the same conditions (-20ºC) as
the field trial samples.  Samples were analyzed immediately after
fortification, and at intervals of 1, 3, 6 and 9.6 months of storage. 
There was no decline in residue during frozen storage; therefore
tribenuron methyl is stable in soybean seeds for intervals of up to 9.6
months.  

	The storage durations and conditions of samples from the corn and
soybean field trial and processing studies submitted to support this
petition are presented in Table 5 (below).  

Table 5	Summary of Storage Conditions and Durations for Samples from the
Field Corn and Soybean Field Trial and Processing Studies.  

Matrix	Storage Temperature (°C)	Actual Storage Duration (Months)
Interval of Demonstrated Storage Stability  (Months)

Field Corn Fodder	-20	12.2	[Wheat grain and straw] 21 1

Field Corn Forage

10.9

	Field Corn Stover

10.5

	Field Corn Grain

11.3

	Corn AGF 2	-20	<1	NA 3

Corn Starch

<1

	Corn Grits

<1

	Corn Flour

<1

	Corn Refined Oil (Wet)

<1

	Corn Refined Oil (Dry)

<1

	Corn Meal

<1

	Soybean Forage	-20	8.3	[Wheat grain and straw] 21 1

Soybean Hay

9.2

	Soybean Seeds

6.9	9.6

Soybean Meal	-20	<1	NA

Soybean Hulls

<1

	Soybean Refined oil

<1

	Soybean AGF

<1

	1. From D304059; R. Griffin; 24 June 2004, and D330633; S. Hummel; 8
August 2006.  

2. AGF = Aspirated Grain Fractions.  

3. NA = Not Applicable.  

	Conclusion:  The available storage stability data adequately support
the sample storage durations and conditions incurred during the corn and
soybean field trial and processing studies.  

860.1400 Water, Fish, and Irrigated Crops

	There are no proposed nor registered uses that are relevant to this
guideline topic.  

860.1460 Food Handling

	There are no proposed nor registered uses that are relevant to this
guideline topic.  

860.1480 Meat, Milk, Poultry, and Eggs

	D304059; R. Griffin; 24 June 2004

	HED has previously concluded that tribenuron methyl residues in
livestock commodities can be classified under 40CFR §180.6[a][3], as
there is no reasonable expectation of detecting finite residues of
tribenuron methyl in milk, eggs, meat or poultry.  This decision was
based on potential dietary exposures of 0.26 ppm for beef and dairy
cattle, and 0.04 ppm for poultry and swine.  

	Based on the recommended tolerances for corn and soybean commodities,
and the established tolerances in other livestock feedstuffs, the
dietary exposures of livestock were calculated using the most recent
guidance from HED (June 2008) concerning revisions to feedstuffs in
Table 1 (OPPTS Residue Chemistry Test Guideline 860.1000), and
construction of maximum reasonably balanced diets (MRBDs) for livestock.
 The newly calculated MRBDs are 0.27 ppm for beef cattle, 0.38 for dairy
cattle, 0.05 ppm for poultry, and 0.05 ppm for swine (see Table 6,
below).  

	In the available goat metabolism study, residues of tribenuron methyl
were not detected (<0.01 ppm) in milk or tissues following 5 days of
dosing with [14C]-triazine- or [14C]-phenyl-labeled tribenuron methyl at
levels equivalent to 6.7 ppm in the diet (17.6-24.8X the MRBD).  Based
on the data from the goat metabolism study, ARIA/RD and HED conclude
that a cattle feeding study is not required for this petition.  

	In the submitted poultry metabolism study, maximum residues of
tribenuron methyl were 0.281 ppm in liver, 0.074 ppm in egg whites,
0.072 ppm in muscle, 0.052 ppm in fat and 0.003 ppm in egg yolks
following 14 days of dosing with [14C]-triazine- or [14C]-phenyl-labeled
tribenuron methyl equivalent to 11.5-11.6 ppm in the diet, which is 231X
the calculated MRBD.  Based on the data from the poultry metabolism
study, residues in liver resulting from the 10X dosing level would be
0.012 ppm; therefore, a poultry feeding study would normally be
required.  

Table 6	Maximum Reasonably Balanced Dietary Burdens on Livestock from
Tribenuron Methyl 		Residues.  

Feedstuff	Type 1	% Dry Matter 2	% Diet 2	Tolerance (ppm)	Dietary
Contribution (ppm) 3

Beef -Cattle (R 15%, CC 80%, PC 5%)

Field corn stover	R	83	10	1.1	0.133

Aspirated grain fractions	R	85	5	1.5	0.089

Barley grain	CC	88	50	0.05	0.029

Sorghum grain	CC	88	30	0.05	0.017

Soybean meal	PC	92	5	0.01	0.0006

TOTAL BURDEN

	100

0.27

Dairy Cattle (R 45%, CC 45%, PC 10%)

Field corn stover	R	83	15	1.1	0.20

Field corn forage	R	40	30	0.2	0.15

Barley grain/sorghum grain	CC	88	45	0.05	0.026

Soybean meal	PC	92	10	0.01	0.0011

TOTAL BURDEN

	100

0.38

Poultry (CC 75%, PC 25%)

Barley grain	CC	88	75	0.05	0.0375

Sunflower seed meal	PC	92	25	0.05	0.0125

TOTAL BURDEN

	100

0.05

Swine (CC 85%, PC 15%)

Barley grain	CC	88	20	0.05	0.01

Sorghum grain	CC	88	65	0.05	0.0325

Sunflower seed meal	PC	92	15	0.05	0.0075

TOTAL BURDEN

	100

0.05

1. R = Roughage; CC = Carbohydrate Concentrate; PC = Protein
Concentrate.  

2. OPPTS Residue Chemistry Test Guideline 860.1000, Table 1 Feedstuffs
(June 2008).  

3. Residue levels for beef and dairy cattle are corrected for moisture
content, and dietary burden contributions are 	determined by formula: 
Contribution = ([tolerance ÷ %DM] x %diet).  Residue levels for poultry
and swine 	are considered “as-is,” and dietary burden contributions
are determined by formula:  Contribution = 	(tolerance x %diet).  

	Conclusion:  Based on the data from the poultry metabolism study,
residues in liver resulting from the 10X dosing level would be 0.012
ppm.  Normally, a poultry feeding study would be required (due to
residues being detected above 0.01 ppm at the 10X dosing level), but
none were previously requested.  Because no significant poultry feed
items are associated with the current petitions, a poultry feeding study
is not required at this time.  However, should the registrant submit any
future petition proposing use on a commodity (or commodities) associated
with poultry feed items, a poultry feeding study will be required, and
that study should be submitted in conjunction with any such petition.  

860.1500 Crop Field Trials

	DER for MRID #47542801 (CFTs with Field Corn)

	DER for MRID #47542802 (CFTs with Soybeans)

	DuPont submitted field trial data supporting the use of tribenuron
methyl (50% ai SG) on genetically modified soybeans and field corn, as a
single post-emergence application at 0.03 lb ai/A.    SEQ CHAPTER \h \r
1 The results from these field trials are discussed below, and the
residue data are summarized in Table 7 (below).  

Table 7	Summary of Residue Data from Soybean and Field Corn Trials with
Tribenuron Methyl.  

Commodity	Trt #	Total Use Rate

(lb ai/A)	PHI (Days)	Residue Levels (ppm) 1





n	Min.	Max.	HAFT 2	Median	Mean	Std. Dev.

Field Corn

Forage	1	0.03	6-8	48	<0.01	0.19	0.11	0.02	0.03	0.034

Stover

	23-63	48	<0.01	0.07	0.07	0.01	0.02	0.014

Grain

	26-63	48	<0.01	<0.01	<0.01	<0.01	<0.01	0

Stover	3	0.03	5-22	48	<0.01	1.20	0.98	0.15	0.25	0.272

Grain

	5-12	48	<0.01	<0.01	<0.01	<0.01	<0.01	0

Forage	6	0.03	23-71	48	<0.01	<0.01	<0.01	<0.01	<0.01	0

Stover

	50-106	48	<0.01	0.02	0.02	0.01	0.01	0.001

Grain

	55-106	46	<0.01	<0.01	<0.01	<0.01	<0.01	0

Soybeans

Forage 3	2	0.03	0	36	0.58	3.00	2.95	1.45	1.71	0.69



	14 4	36	0.009	0.046	0.045	0.022	0.026	0.011

Hay 3

	0	36	0.61	8.80	8.35	2.75	3.54	2.52



	14 4	36	0.013	0.185	0.175	0.058	0.074	0.053

Seeds

	68-107	44	<0.01	<0.01	<0.01	<0.01	<0.01	0

Seeds	4	0.03	5-8	44	<0.01	0.07	0.07	0.01	0.01	0.01

1. The LOQ is 0.010 ppm for each commodity.  For calculations which
included residues >LOQ, the method LOQ 	(0.010 ppm) was used for residue
values <LOQ.  

2. HAFT = Highest Average Field Trial.  

3. Residue data on soybean forage and hay were not included from Trials
#2, 5, 6, 20 and 21 due to anomalies in 	either the application rate or
sampling interval.  

4. Residue data for the 14-day PHI were extrapolated from the 0-day data
using the decline rate of the longest 	residue decline curve from the
residue decline field trials.  

	Field Corn:  DuPont submitted field trial data supporting the use of
tribenuron methyl (50% ai SG) on field corn that is genetically modified
to be tolerant to sulfonylurea herbicides.  Twenty-four field trials,
each including three different treatment regimes, were conducted in
Zones 1, 2, 5 and 6 during 2006.  At each trial, a 50% ai SG formulation
of tribenuron methyl was applied to field corn as a single broadcast
foliar application at 0.03 lb ai/A, approximately 7 days prior to normal
forage harvest (Trt #1), 7 days prior to grain harvest (Trt #3), or at
growth stage R1-R2 (Trt #6).  All applications were made using ground
equipment, in spray volumes of 5-30 gallons per acre (GPA), and included
the use of a non-ionic surfactant (NIS) at 0.25% v/v.  

	Single control and duplicate treated samples of the appropriate
commodities were harvested from each test at the appropriate stage of
maturity.  For Trt #1, forage was harvested at 6-8 days after treatment
(DAT), stover was harvested at 23-63 DAT, and grain was harvested at
26-63 DAT.  For Trt #6, forage was harvested at 23-71 DAT, stover was
harvested at 50-106 DAT, and grain was harvested at 55-106 DAT.  For Trt
#3, only samples of stover and grain were harvested at 5-22 and 5-12
DAT, respectively.  Duplicate repeated samples of forage and/or stover
were also collected from Trts #1, #3 and #6 at five field trials, in
order to evaluate residue decline.  For Trt #1, forage samples were
collected repeatedly from 0-22 DAT, and stover samples were collected
repeatedly from 23-84 DAT.  For Trt #3, stover samples were collected
repeatedly from 6-28 DAT.  For Trt #6, forage samples were collected
repeatedly from 0-68 DAT.  

	Samples were stored frozen for up to 12.2 months prior to analysis. 
Adequate storage stability data are available indicating that tribenuron
methyl is stable at -20°C for intervals of up to 21 months in wheat
grain and straw, and up to 6 months in corn forage.  These data will
support the durations and conditions of samples harvested from the corn
field trials.  

	Residues of tribenuron methyl in corn grain, forage and stover were
determined using an adequate LC/MS/MS method (Method 13412, Revision 1).
 The method LOQ is 0.010 ppm, and the LOD is 0.003 ppm in each corn
commodity.  

	Following a single broadcast foliar application at 0.03 lb ai/A (1X
rate), applied approximately 7 days prior to normal forage harvest (Trt
#1), tribenuron methyl residues were <0.01-0.19 ppm in 48 samples of
forage harvested at 6-8 DAT, <0.01-0.07 ppm in 48 samples of stover
harvested at 23-63 DAT, and <LOD in all 48 samples of grain harvested at
26-63 DAT.  Average residues were 0.03 ppm for forage, 0.02 ppm for
stover, and <0.01 ppm for grain.  The highest average field trial (HAFT)
residues were 0.11 ppm for forage, 0.07 ppm for stover, and <0.01 ppm
for grain.  

≤0.01 ppm for forage, stover and grain, while the HAFT residues were
0.02 ppm for stover, and <0.01 ppm for forage and grain.  

	When the single foliar application was applied at 0.03 lb ai/A,
approximately 7 days prior to normal grain maturity (Trt #3), residues
were <LOD in all samples of grain harvested at 5-12 DAT, and <0.01-1.20
ppm in 48 samples of stover harvested at 5-22 DAT.  Average residues
were <0.01 ppm for grain, and 0.25 ppm for stover, while the HAFT
residues were <0.01 ppm for grain, and 0.98 ppm for stover.  

	In the five residue decline trials, tribenuron methyl residues in
forage (Trt #1 and #6) showed a rapid decline within the first 7 DAT,
and then declined more slowly until residues were generally <0.05 ppm by
22 DAT.  Changes in residue levels in stover (Trt #1 and #3) were more
sporadic than for forage, but tribenuron methyl residues in stover
generally declined or remained steady at longer post-treatment
intervals.  

	Soybeans:  DuPont submitted field trial data supporting the use of
tribenuron methyl (50% ai SG) on soybeans that are genetically modified
to be tolerant to sulfonylurea herbicides.  Twenty-three soybean field
trials, each including two different treatment regimes, were conducted
in Zones 2, 4 and 5 during 2006.  At each trial, tribenuron methyl (50%
ai SG) was applied to soybeans as a single broadcast foliar application
at 0.03 lb ai/A (1X rate), at growth stage R1-R2 (Trt #2), or
approximately 7 days prior to normal seed harvest (Trt #4).  In one test
(Trial 02), the tribenuron methyl (50% ai SG) was applied under both
treatment regimes at 0.06 lb ai/A (2X rate).  All applications were made
using ground equipment, in spray volumes of 5-27 GPA, and included the
use of a non-ionic surfactant at 0.25% v/v.  

	For Trt #2, single control and duplicate treated samples of forage and
hay were harvested on the day of application (0 DAT), while seeds were
harvested at normal maturity (68-107 DAT).  Repeated samples of forage
and hay were also collected from three trials at 0, 1, 3, 7, 14 and 21
DAT, in order to evaluate residue decline.  For Trt #4, single control
and duplicate treated samples of seeds were harvested at 5-8 DAT. 
Samples were stored frozen for up to 9.2 months prior to analysis.
Adequate storage stability data are available indicating that tribenuron
methyl is stable at -20°C for intervals of up to 6 months in corn
forage, 21 months in wheat grain and straw, and 9.6 months in soybean
seeds.  These data support the durations and conditions of samples
harvested from the soybean field trials.  

	Residues of tribenuron methyl in soybean forage, hay and seeds were
determined using an adequate LC/MS/MS method (Method 13412, Revision 1).
 The method LOQ is 0.010 ppm, and the LOD is 0.003 ppm in each soybean
commodity.  

	Following a single broadcast foliar application at 0.03 lb ai/A (1X
rate), at growth stage R1-R2 (Trt #2), tribenuron methyl residues were
0.58-3.0 ppm in 36 samples of forage, 0.61-8.80 ppm in 36 samples of hay
harvested at 0 DAT, and <0.01 ppm in all 44 samples of seeds harvested
at 68-107 DAT.  Average residues were 1.71 ppm for forage, 3.54 ppm for
hay, and <0.01 ppm for seeds.  The HAFT residues were 2.95 ppm for
forage, 8.35 ppm for hay, and <0.01 ppm for seeds.  Note:  Although
residue data were submitted from 23 trials (46 samples), residue data
for forage and hay from 5 tests were excluded from the dataset because
of anomalies in either the application rate or the sampling intervals.  

	When the single foliar application was applied at 0.03 lb ai/A,
approximately 7 days before normal crop maturity (Trt #4), residues were
<0.01-0.07 ppm in 44 samples of seeds harvested at 5-8 DAT.  The average
residue in seeds was 0.01 ppm, while the HAFT residue was 0.07 ppm.  

	For both forage and hay, tribenuron methyl residues declined rapidly
within the first week after application, and then declined more slowly
thereafter.  For all three decline tests, average residues in forage
were 1.72 ppm at 0 DAT, 0.04 ppm by 7 DAT, and <0.01 ppm by 21 DAT. 
Average residues in hay were 3.83 ppm at 0 DAT, 0.05 ppm by 7 DAT, and
<0.01 ppm by 21 DAT.  

	The use pattern being supported on soybeans by DuPont is Trt#2;
however, the petitioner is requesting a 14-day PHI for forage and hay,
rather than a 0-day PHI, which is supported by the available residue
data.  Based on the data from the residue decline studies, DuPont used
the rate constant from the decline curve with the longest rate of
decline to extrapolate possible residue values for soybean forage and
hay at the proposed 14-day PHI.  The formula shown below was used to
calculate 14-day residue values for forage and hay.  

ln(residues at 14 days) = m(14) + ln(residues at 0 DAT)

The rate of decline (m) was calculated to be -0.298 for soybean forage,
and -0.276 for soybean hay.  The extrapolated 14-day residue values for
forage and hay are presented in Appendix I, and are summarized in Table
7, above.  

	Conclusions:  The available corn and soybean field trial data are
acceptable, and support the proposed use patterns for tribenuron methyl
(50% ai SG) on genetically modified soybeans and field corn.  An
adequate number of trials were conducted on each crop in the appropriate
geographical regions.  All samples were analyzed for the ROC using an
adequate method, and sample storage conditions and durations are
supported by the available storage stability data.

	The field trial data support the proposed 7-day PHI for all corn
commodities, and the proposed 14-day PHI for soybean forage and hay.  As
the label directions for use on soybeans prohibit applications after the
R2 stage, a specific PHI for soybean seeds is not required.  The data
support tolerances of 0.01 ppm in/on corn grain, 0.15 ppm in/on corn
forage, 1.1 ppm in/on corn stover, 0.01 ppm in/on soybean seeds, 0.07
ppm in/on soybean forage, and 0.35 ppm in/on soybean hay.  

 

860.1520 Processed Food and Feed

	DER for MRID #47548203 (PFF from Field Corn)

	DER for MRID #47548204 (PFF from Soybeans)

	Field Corn:  DuPont has submitted data from 3 field trials conducted in
IA and NE during 2006 used to generate field corn grain for use in
processing (2 tests) or for generating AGF (1 test).  In the test used
to generate AGF samples, tribenuron methyl (50% ai SG) was applied as a
single broadcast foliar application, 7 days prior to normal grain
maturity, at the rate of 0.031 lb ai/A (1X rate).  In the two tests used
to generate grain for processing, tribenuron methyl (50% ai SG) was
applied as a single broadcast foliar application 7 days prior to normal
harvest at a rate of 0.15 lb ai/A (5X rate).  All applications were made
using ground equipment, in spray volumes of 16-20 GPA, and included the
use of a non-ionic surfactant at 0.25% v/v.  

	Single bulk control and treated sample of corn grain, the raw
agricultural commodity (RAC), were harvested from each test at 7 DAT. 
AGF samples were generated using corn grain from the 1X rate test, via
procedures designed to simulate the movement of grain through terminal
elevators.  Corn grain samples from the 5X rate tests were processed,
using simulated commercial milling procedures, into starch, grits, meal,
flour and refined oil (wet- and dry-milled).  Samples of corn grain were
stored frozen for up to 6.5 months prior to analysis, while corn AGF and
processed commodities were stored frozen for ≤30 days prior to
analysis.  These sample storage conditions and durations are supported
by the available storage stability data.  

	Residues of tribenuron methyl in corn grain, AGF and processed
fractions were determined using an adequate LC/MS/MS method (Method
13412, Revision No. 1).  The method LOQ is 0.010 ppm, and the LOD is
0.003 ppm in each corn commodity.  

	In the test used to generate AGF, tribenuron methyl residues were <LOD
in the grain harvested at 7 DAT following an application at the 1X rate.
 Residues in AGF averaged 0.039 ppm, indicating that tribenuron methyl
residues can concentrate by up to 13X in corn AGF.  Following an
application at the 5X rate, residues of tribenuron methyl were <LOQ in
corn grain and all processed fractions from both processing studies (see
Table 8, below).  

	Soybeans:  Three soybean field trials were conducted in IL, MN and NE
during 2006, in order to generate soybean seed samples for processing (2
tests), and for generating AGF (1 test).  In the test used to generate
AGF samples, tribenuron methyl (50% ai SG) was applied as a single
broadcast foliar application, 5 days prior to normal seed maturity, at
the rate of 0.03 lb ai/A (1X rate).  In the two tests used to generate
seeds for processing, tribenuron methyl (50% ai SG) was applied as a
single broadcast foliar application, 7 days prior to normal harvest, at
the rate of 0.16 lb ai/A (5X rate).  All applications were made using
ground equipment, in spray volumes of 15-25 GPA, and included the use of
a non-ionic surfactant at 0.25% v/v.  

	Single bulk control and treated samples of soybean seeds (RAC) were
harvested from each test at 5 or 7 DAT.  AGF samples were generated
using seeds from the 1X rate test, via procedures designed to simulate
the movement of grain through terminal elevators.  Soybean seeds from
the 5X rate tests were processed using simulated commercial procedures
into hulls, meal and refined oil.  Samples of soybean seeds were stored
at ≤-12° C for up to 2 months prior to analysis, while soybean AGF
and processed commodities were stored frozen for ≤30 days prior to
analysis.  These sample storage conditions and durations are supported
by the available storage stability data.  

	Residues of tribenuron methyl in soybean seeds, AGF and processed
fractions were determined using an adequate LC/MS/MS method (Method
13412, Revision No. 1).  The method LOQ is 0.010 ppm, and the LOD is
0.003 ppm in each soybean commodity.  

	In the test used to generate AGF, tribenuron methyl residues were <LOD
in the seeds harvested at 5 DAT following an application at a 1X rate. 
Residues in AGF averaged 0.45 ppm, indicating that tribenuron methyl
residues can concentrate by up to 150X in soybean AGF.  

	For the 5X tests, tribenuron methyl residues in whole seeds were <LOD
in one test and 0.042 ppm in the other test.  For the test with
quantifiable residues in seeds, residues averaged 0.17 ppm in hulls, and
<LOD in meal and refined oil.  Tribenuron methyl residues concentrated
by 4.05X in hulls, and were reduced by <0.07X in meal and refined oil.  

  SEQ CHAPTER \h \r 1 Table 8	Summary of Processing Factors for
Tribenuron Methyl.  

RAC	Processed Commodity	Processing Factor

Corn Grain 	AGF	13X

	Processed fractions	Not calculated.*

Soybean Seeds	AGF	150X

	Hulls	4.05X

	Meal	<0.07X

	Refined oil	<0.07X

*Processing factors for field corn were not calculated, as residues were
<LOQ in grain and all processed fractions.  

	Conclusions:  The available corn and soybean processing data for
tribenuron methyl are adequate.  As residues were <LOQ in corn grain,
and all corn processed fractions following an application at 5X the
proposed use rate, separate tolerances are not required in corn grain
processed fractions.  For soybeans, residues concentrated only in hulls
(4.05X).  Based on HAFT residues of 0.01 ppm for soybean seeds (14-day
PHI), the tolerance in/on soybean hulls should be set at 0.04 ppm.  

	Tribenuron methyl residues were shown to concentrate in AGF from both
field corn grain (13X), and soybean seeds (150X).  Based on the HAFT
residues of field corn grain (0.01 ppm), and soybean seeds (0.01 ppm),
the maximum expected residues would be 0.13 ppm in AGF from corn grain,
and 1.5 ppm in AGF from soybean seeds.  As residues in soybean AGF are
higher than in corn grain AGF, the tolerance in/on AGF should be set at
1.5 ppm.  

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

	An analytical standard for tribenuron methyl is currently available in
the National Pesticide Standards Repository (personal communication with
T. Cole, BEAD/ACB).  

860.1850 and 860.1900  Confined and Field Accumulation in Rotational
Crops

	D304059; R. Griffin; 24 June 2004

	Adequate confined rotational crop data are available to support a
minimum 30-day PBI for all crops without registered uses.  As labels for
tribenuron methyl currently specify minimum PBIs of no less than 60 days
for canola, rape and sugar beets, and 45 days for all other crops not
listed on the label, data requirements for rotational crops are
fulfilled, and tolerances are not required in rotational crops.  

860.1550 Proposed Tolerances

	Permanent tolerances for residues of tribenuron methyl have been
established in/on barley, canola, field corn, cotton, flax, grass, oat,
rice, sorghum, soybean, sunflower and wheat commodities, at levels
ranging from 0.02 to 0.5 ppm (40CFR §180.451[a] and [c]).  No
tolerances have been established for residues in either animal
commodities or rotational crops.  The proposed and recommended
tolerances are presented in Table 9, below.  

	As residues were <LOQ in all samples of soybean seeds, and field corn
grain collected at the appropriate PHIs, the recommended tolerances in
these commodities are equal to the method LOQ (0.010 ppm).  For field
corn forage and stover, and soybean forage and hay, tolerances were
calculated using the tolerance harmonization spreadsheet (Appendix I). 
The residue data supporting the 7-day PHI were used to calculate
tolerances in field corn forage and stover.  For soybean forage and hay,
the 0-day residue data were extrapolated to a 14-day PHI, based on the
observed residue decline data.  The calculated 14-day residues were then
used to determine the appropriate soybean tolerances.  

	As residues were <LOQ in corn grain, and all corn processed fractions
following an application at 5X the proposed use rate, separate
tolerances are not required in corn grain processed fractions.  For
soybeans, residues concentrated only in hulls (4.05X).  Based on HAFT
residues of 0.01 ppm for soybean seeds (14-day PHI), the appropriate
tolerance in soybean hulls is 0.04 ppm.  

	Tribenuron methyl residues were shown to concentrate in AGF from both
corn grain (13X), and soybean seeds (150X).  Based on the HAFT residues
for field corn grain (0.01 ppm), and soybean seeds (0.01 ppm), the
maximum expected residues would be 0.13 ppm in AGF from corn grain, and
1.5 ppm in AGF from soybean seeds.  As residues in soybean AGF are
higher than in corn grain AGF, the recommended tolerance in AGF is 1.5
ppm.  

	Based on the MRDBs on livestock, and the available metabolism studies,
finite residues of tribenuron methyl are not expected to occur in
cattle, goat, horse, sheep nor hog commodities (40CFR §180.6[a][3]). 
Finite residues are also not expected to occur in eggs, poultry meat,
nor poultry fat.  Based on the available metabolism data, detectable
residues could possibly occur in poultry meat byproducts.  However,
because no significant poultry feed items are associated with the
current petitions, a poultry feeding study is not required at this time.
 

	There are no established nor proposed Codex or Mexican MRLs for
residues of tribenuron methyl (Appendix II).  Canada has established
MRLs for tribenuron methyl in several plant commodities.  However, no
Canadian MRLs for tribenuron methyl have been proposed nor established
in the commodities being considered under these petitions.  Therefore,
there are no concerns regarding compatibility of the proposed
tolerances.  

	There are no residue chemistry considerations that would preclude
establishing permanent tolerances for residues of tribenuron methyl,
including its metabolites and degradates, in or on the commodities
specified in Table 9, below. Compliance with the tolerance levels
specified below is to be determined by measuring tribenuron methyl only.
 

Table 9	Tolerance Summary for Tribenuron Methyl.  

Commodity	Proposed Tolerance (ppm)	Recommended Tolerance (ppm)	Comments;

Correct Commodity Definition

Corn, field, grain	0.01	0.01	Adequate residue data are available. 
Residues were <0.01 ppm in all grain samples.  

Corn, field, forage	0.2	0.15	Adequate residue data on forage are
available supporting the 7-day PHI.  The tolerance was calculated using
the tolerance spreadsheet.  

Corn, field, stover	1.1	1.1	Adequate residue data on stover are
available supporting the 7-day PHI.  The tolerance was calculated using
the tolerance spreadsheet.  

Corn, aspirated grain fractions	3.45	None	Adequate residue data are
available indicating that residues concentrate in corn grain AGF by 13X.
 Based on a HAFT of 0.01 ppm for corn grain, the maximum expected
residues in corn grain AGF would be 0.13 ppm.  

Soybean, hay	0.25	0.35	Adequate residue data are available on soybean
forage and hay harvested at 0 DAT.  These data were extrapolated to
calculate residues at 14 DAT, which is the proposed PHI for forage and
hay.  Tolerances were calculated using the tolerance spreadsheet.  

Soybean, forage	0.06	0.07

	Soybean, seed	0.01	0.01	Adequate residue data are available supporting
application at the R2 Stage. Residues were <0.01 ppm in all seed
samples.  

Soybean, hulls	0.04	0.04	Adequate residue data are available.  Based on
a processing factor of 4.0X for hulls, and a HAFT of 0.01 ppm for
soybean seeds, the maximum expected residues in hulls would be 0.04 ppm.
 

Soybean, aspirated grain fractions	3.55	None	Adequate residue data are
available, indicating that residues concentrate in soybean AGF by 150X. 
Based on a HAFT of 0.01 ppm for soybean seeds, the maximum expected
residues in soybean AGF would be 1.5 ppm.  

Grain, aspirated fractions	None	1.5	A single tolerance should be
established in Grain, aspirated fractions, based on the soybean AGF
data.  



References

	Tribenuron methyl.  Residue Chemistry Considerations.; D304059; R.
Griffin; 24 June 2004.  

	Thifensulfuron methyl.  Addition of Uses on Rice and Sorghum (PRIA R19
– 352-611; PP#4F6889).  Summary of Analytical Chemistry and Residue
Data.; D330813; S. Hummel; 8 August 2006

	Tribenuron methyl.  Addition of Preplant Burndown Uses on Field Corn,
Rice, Sorghum, and Soybeans (PRIA R19; PP#4F6890) and Postemergence Uses
on Sunflower (IR-4 Request; PP#4E6855).  Summary of Analytical Chemistry
and Residue Data.; D330633; S. Hummel; 8 August 2006

  SEQ CHAPTER \h \r 1 Attachments:  

Appendix I - Tolerance Assessment Calculations

Appendix II - International Residue Limit Status sheet

Appendix I - Tolerance Assessment Calculations

	For each of the crops listed below, the Guidance for Setting Pesticide
Tolerances Based on Field Trial Data SOP, along with the tolerance
spreadsheet, was used for calculating recommended tolerances.  As
specified in the SOP, the minimum of the 95% upper confidence limit
(UCL) on the 95th percentile, and the point estimate of the 99th
percentile, was selected as the tolerance value in cases where the
dataset was large (greater than 15 samples) and reasonably lognormal. 
For datasets that were small (≤15 samples) and reasonably lognormal,
the upper bound estimate of the 95th percentile (based on the median
residue value) was compared to the minimum of the 95% UCL on the 95th
percentile, and the point estimate of the 99th percentile, and the
minimum value was selected as the tolerance value.  For datasets that
were not lognormal, the upper bound on the 89th percentile was selected
as the tolerance value (distribution-free method).  The rounding
procedures specified in the SOP were also used.  

	The Agency’s Guidance for Setting Pesticide Tolerances Based on Field
Trial Data was utilized for determining the appropriate tolerance levels
in field corn forage and stover harvested at 6-8 DAT, and soybean forage
and hay harvested at 0 DAT (and extrapolated to 14 DAT).  However, the
tolerance spreadsheet was not used to calculate the tolerance in field
corn grain, or soybean seeds, as the datasets for these commodities
contained high percentages of (or all) values <LOQ.  For corn grain, all
samples, regardless of PHI, were <LOQ.  For soybeans, samples of seeds
harvested following the harvest of hay (68-107 DAT) were all <LOQ.  For
seed samples harvested 5-8 DAT, 84% of the residues were <LOQ.  The
datasets for corn forage and stover, and soybean forage and hay, are
presented in Tables I-1 and I-2.  

	Those datasets used to assess a possible tolerance for tribenuron
methyl residues in corn forage harvested at 6-8 DAT, corn stover
harvested at 5-7 DAT, and soybean forage and hay harvested at 0 DAT (and
extrapolated to 14 DAT), consist of field trial data representing
applications of the appropriate formulation, at rates approximately 1X
the maximum proposed use rates.  As specified by the Guidance for
Setting Pesticide Tolerances Based on Field Trial Data SOP, the field
trial application rates were within 25% of the maximum label application
rates.  

	Corn:  The datasets for tribenuron methyl residues in corn forage
harvested at 6-8 DAT, and corn stover harvested at 5-7 DAT, were entered
into the tolerance spreadsheet.  Visual inspection of the lognormal
probability plots (Figures I-1 and I-3) indicated that the datasets are
somewhat or reasonably lognormal.  However, the results of the
approximate Shapiro-Francia test statistic rejected this assumption for
both forage and stover (Figures I-2 and I-4).  

	The recommended tolerances in corn forage harvested at 6-8 DAT, and in
corn stover harvested at 5-7 DAT, are 0.15 and 1.1 ppm, respectively.  

	Soybean:  The datasets for tribenuron methyl residues in soybean forage
and hay harvested at 0 DAT (and extrapolated to 14 DAT) were entered
into the tolerance spreadsheet.  Visual inspection of the lognormal
probability plots (Figures I-5, I-7, I-9 and I-11) indicated that the
datasets for forage and hay, at both harvest intervals, are lognormal. 
The results of the approximate Shapiro-Francia test statistic confirm
these assumptions (Figures I-6, I-8, I-10 and I-12).  

	The recommended tolerances in soybean forage and hay, harvested at 0
DAT, are 4.5 and 15 ppm, respectively.  When the residue data from 0 DAT
are extrapolated out to 14 DAT, the recommended tolerances in soybean
forage and hay are 0.07 ppm and 0.35 ppm, respectively.  

Table I-1	Tribenuron Methyl Residues in Field Corn Forage and Stover.  

Regulator:	EPA

Chemical:	Tribenuron methyl

Crop:	Corn forage	Corn stover

PHI:	6-8 days	5-7 days

Application Rate:	0.03 lb ai/A	0.03 lb ai/A

Submitter:	DuPont	DuPont

MRID Citation:	MRID #47548201	MRID #47548201

	Residues	Residues

	0.010	0.019	0.010	0.19

	0.010	0.019	0.010	0.21

	0.010	0.020	0.010	0.25

	0.010	0.021	0.010	0.26

	0.010	0.021	0.010	0.29

	0.010	0.021	0.010	0.29

	0.010	0.023	0.024	0.3

	0.010	0.024	0.026	0.3

	0.010	0.026	0.049	0.31

	0.010	0.028	0.058	0.32

	0.010	0.032	0.067	0.32

	0.010	0.034	0.068	0.34

	0.010	0.039	0.07	0.4

	0.011	0.039	0.07	0.41

	0.012	0.041	0.083	0.42

	0.012	0.044	0.087	0.42

	0.012	0.062	0.087	0.43

	0.013	0.063	0.094	0.49

	0.013	0.067	0.10	0.6

	0.013	0.095	0.10	0.69

	0.014	0.100	0.13	0.85

	0.014	0.120	0.15	1.1

	0.016	0.190	0.15	1.2

NOTE:  Values at or below the LOQ (0.010 ppm) are entered as the LOQ,
and are listed in bold red.  



Figure I-1.	Lognormal Probability Plot for Residues of Tribenuron Methyl
in Corn Forage Harvested 6-8 DAT

Figure I-2.	Data Summary Table for Residues of Tribenuron Methyl in Corn
Forage Harvested 6-8 DAT.

Figure I-3.  	Lognormal Probability Plot for Residues of Tribenuron
Methyl in Corn Stover harvested 5-7 DAT.

Figure I-4.  Data Summary Table for Residues of Tribenuron Methyl in
Corn Stover harvested 5-7 DAT.



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	2.90	0.045	7.9	0.166

	2.90	0.045	8.2	0.172

	3.00	0.046	8.8	0.185

NOTES:  Values at or below the LOQ (0.010 ppm) are entered as the LOQ,
and are listed in bold red.  The formula shown below was used to
calculate the 14-day residue values for forage and hay.  

			ln(residues at 14 days) = m(14) + ln(residues at 0 DAT)



Figure I-5.	Lognormal Probability Plot for Residues of Tribenuron
Methyl in Soybean Forage Harvested at 0 DAT.

Figure I-6.	Data Summary Table for Residues of Tribenuron Methyl in
Soybean Forage Harvested at 0 DAT.

Figure II-7.	Lognormal Probability Plot for Residues of Tribenuron
Methyl in Soybean Forage Extrapolated to a 14-day PHI.

Figure I-8.	Data Summary Table for Residues of Tribenuron Methyl in
Soybean Forage Extrapolated to a 14-day PHI.

Figure I-9.	Lognormal Probability Plot for Residues of Tribenuron Methyl
in Soybean Hay Harvested at 0 DAT.

Figure I-10.	Data Summary Table for Residues of Tribenuron Methyl in
Soybean Hay Harvested at 0 DAT.

Figure I-11.	Lognormal Probability Plot for Residues of Tribenuron
Methyl in Soybean Hay Extrapolated to a 14-day PHI.

Figure I-12.	Data Summary Table for Residues of Tribenuron Methyl in
Soybean Hay Extrapolated to a 14-day PHI.

Appendix II - International Residue Limit Status Sheet

INTERNATIONAL RESIDUE LIMIT STATUS



Chemical Name: Methyl-2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)
methylamino] carbonyl] amino] sulfonyl] benzoate	

Common Name:  

Tribenuron methyl	

X Recommended tolerances

( Reevaluated tolerance

( Other 	

Date: 8 July 2009

Codex Status (Maximum Residue Limits)	US Tolerances

X No Codex proposal step 6 or above

( No Codex proposal step 6 or above for the crops requested  	Petition
Numbers:  8F7432, 8F7441

DP Number:  360846

Other Identifier:  PC code 128887

Residue definition (step 8/CXL):  NA	Reviewer, Division/Branch/Team: 
William T. Drew,  RD/RIMUERB/ARIA

	Residue definition: Tribenuron methyl

Crop	MRL (mg/kg)	Crops	Tolerance (ppm)



Corn, field, grain	0.01



Corn, field, forage	0.15



Corn, field, stover	1.1



Soybean, hay	0.35



Soybean, forage	0.07



Soybean, seed	0.01



Soybean, hulls	0.04



Grain, aspirated fractions	1.5

Limits for Canada	Limits for Mexico

( No Limits

X No Limits for the crops requested	X No Limits

( No Limits for the crops requested

Residue definition:
Methyl-2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)methylamino]carbonyl
]amino] sulfonyl]benzoate	Residue definition:  NA

Crop	MRL (mg/kg)	Crop	MRL (mg/kg)































Notes/Special Instructions:  NA = Not Applicable.  Per Steve Funk, 20
July 2009.  



Page   PAGE  31  of   NUMPAGES  31 

Tribenuron Methyl	Summary of Analytical Chemistry and Residue Data	DP
Number:  360846

